In many contexts, it is advantageous to know whether and which animals have been or are present in a certain location, their density, and the length of time they have stayed in and/or likely remain within the given location. One context in which it is important to have this information is marine shipping. It is advantageous for marine vessels to know, for example, whether and to what extent marine mammals, such as cetaceans, are in the same area in which marine vessels are or will be traveling—not only to protect the cetaceans but also the vessels. It is important also for operators of fishing boats to know whether certain fish were and possibly remain in a certain area. Businesses that operate eco-tours—that is, tours that often feature viewing animals that live in a particular area—seek to take their customers to areas on land or on the water in which they are more likely to view the animals.
Certain of these commercial interests seek to obtain and use information regarding a certain subject contemporaneously as the information and data is collected. Aerial surveys, for example, can provide contemporaneous information regarding subjects. Such surveys are used to determine, for example, animal presence, distribution, movement, use of habitat, and density. A variety of disadvantages are associated with such surveys. For example, aerial surveys are costly, often provide information only during daylight hours, and, unless repeated, cannot provide historical information that can place the contemporary data in a larger context.
Other commercial interests because of their nature must deploy systems that can operate directly in a given environmental context and be able to collect a body of information from which it can be reliably determined the identity of subjects that were present in the area and whether they may be likely remain in the area.
Passive acoustic detection, or passive acoustic monitoring (collectively “PAM”) systems use sensors that are deployable in marine and terrestrial contexts to collect sound information and one or more recorders to record the sound information thereby permitting a body of sound data to be amassed. Because animals often produce sounds by which each animal can be identified, PAM systems can help determine what animals are present in the given marine or terrestrial ecosystem. Systems that can detect sounds of biological origin can detect also any sound including those generated by vehicles, ships, and other subjects and produced because of natural phenomena. Such systems that use sounds from animals, vehicles, and other sources of anthropogenic sounds and noise for identification purposes are considered to be a useful cost-efficient complement or alternative to aerial surveys. PAM systems can more easily provide information regarding animal distribution, habitat use, and relative density.
Advantageously, PAM systems can be used to collect and record a large amount of data. A wide variety of commercial interests seek access to and the use of this data. For example, currently government agencies, oil and gas companies, environmental companies, and non-profit groups seek to obtain access to and use the large bodies of acoustical data recordings obtained using terrestrial or underwater arrays of sensors in order to extract the information that they need.
Many techniques exist that are intended to help with the organization and analysis of large bodies of acoustic data in order that select certain information can be extracted from the data. Data analysis includes, but not limited to, the detection of sounds from only one or more certain subjects—the “signals of interest” or “SOI” in this application. Data analysis can include also the evaluation of the distribution of the SOI over time, whether one or more of the features of the SOI change over time, and whether and to what extent ambient noise exists in the area in which the SOI is found and the possible source of the ambient noise.
A reliable and accurate way of extracting useful information from the data collected through the passive acoustic monitoring of marine and terrestrial ecosystems is through the visual analysis of the digital acoustical recordings. A number of commercial products have been offered to allow the visual analysis of digital acoustical data. However, the data visualization and extraction techniques implemented in the existing commercial products often enable only a small portion of long-term data recordings—in some cases ten percent or less—to be processed with an acceptable accuracy and quality, given typical budgetary and times constraints. Some of existing products for the visual analysis of the recorded acoustic data and detection of SOI permit a user to view a sound spectrogram and a time series. In some cases, the offered spectrogram does provide enough information to permit a viewer to determine whether a SOI is present in a given selection of data taken from a larger body of data. However, spectrograms developed through the use of conventional data analysis systems take large portions of the typical screen used for the display of the spectrograms. As a result, the amount of data that can be offered to a viewer at any one time is limited. A viewer seeking to analyze and view as spectrograms a large amount of data—such as the entire body of data recorded over a particular time or for a particular event—must be prepared to devote an equally large amount of time given that the display must be changed to show all related spectrograms. The amount of time needed to analyze an entire data set through conventional methods linearly increases as the amount of time that was spent to collect the data. It is difficult also for a user to readily determine whether any pattern exists in the recorded data given that all the data is typically not shown on a single screen.
Therefore there is a need for a system and methods by which large bodies of acoustic data can be analyzed and, for example, one or more signals of interest identified quickly and reliably. The present invention satisfies this demand.